`sd` package: `sdcard` package redesign

[soypat]

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New Features:

• Idiomatic CSD V1,V2 support with V3 API compatibility
• No heap allocations
• Complete error handling
• CRC support
• Design for interface compatibility with other SDCard implementations i.e. Using raw SDIO with a Raspberry Pi Pico.
• Added tests for what is testable
• Renamed ReadData to more idiomatic ReadBlock, same with Write methods
• More checks for OOB write/read requests
• Allow multi block writing and multi block reading in a double method interface, making it easier to use.
• Easily enable highest transfer rate available for SDCard using CSD

~Is still a WIP. CRC7 still does not work and I'm getting errors on ever other ReadBlock call.~

[bgould]

Is it possible to make this implement BlockDevice so that it is natively compatible with tinyfs? Skimming definitions.go, it looks there are some similar methods in there

https://github.com/tinygo-org/tinyfs/blob/release/tinyfs.go#L43

[soypat]

@bgould Will do, but I'll do it through another type that uses the ReadBlocks/WriteBlocks interface set to implement the tinyfs.BlockDevice interface. Already had this in mind as the next addition to sd

[soypat]

@bgould I've added a draft of what I mean: https://github.com/tinygo-org/drivers/pull/639/files#diff-92f519b8e01de4c93b473c245b482f67da4e20bfbfbe48aaca799f35e45afb43R38

[soypat]

@bgould OK, I've finished the sd.BlockDevice type, seems to be working OK. Check it out and let me know what you think :)

[deadprogram]

@soypat would you perhaps be able to add a README with some small explanation about how this works?

For example what is rustref.go do? :smile_cat:

[soypat]

OK, added a Readme and switched some filenames around to make navigation easier.

[deadprogram]

@bgould have you had a chance to try this out yet?

[deadprogram]

Paging Dr. @bgould :smile_cat: any chance to try this out?